Re: Alone on L/S ON A0-51

Greg,
There is a way to figure out how much power you are getting to your
mode-L antenna. Times MIcrowave has a on-line calculator for many of
the more popular cables.
http://www.timesmicrowave.com/cgi-bin/calculate.pl
If you use the numbers for LMR-600 (3.056-dB/100-feet) in place of
your 1/2-inch hardline you get:
60-feet of cable: Loss=1.8 dB Efficiency = .656
For RG-214 (8.472-dB/100 feet):
10-feet of cable: Loss=0.8 dB Efficiency = .823
add the loss in dB = 2.6 dB, or multiply the efficiencies = 0.54
So 10w x 0.54 = 5.4w
This is a lot for AO-51.
Ain't math fun ;-)
73 Ed - KL7UW
At 02:22 PM 9/13/2008, Greg D. wrote:
>Hi Robert,
>
>The equipment is my receive side from my AO-40 setup, along with a
>newly acquired transmit side.
>
>The receive side starts with a home made 3 3/4 turn helix in the
>bottom inch of a grapefruit juice can, which makes up the feed for a
>BBQ grill antenna that I lined with window screen in order to make
>it usable for circularly polarization. There's a Khune 2.4 ghz
>preamp (highly recommended!) attached to the feed, and a short cable
>to one of those infamous Drake downconverters. I modified the Drake
>in an unusual way, moving the local oscillator from whatever it was
>to 2100 mHz. That put AO-40's 2401.3xx mHz downlink in the middle
>of the Drake's design passband, and in a nice place between our 2m
>and 70cm bands so that I could use either as an uplink without
>interference. There's about 60' of Quad-shield RG-6 out the back of
>the Drake to the shack. where it terminates on a power injector
>connected to a multi-way Radio Shack RF (video) switch. The switch
>allows me to select our pre-Cable TV antenna (never throw anything
>away!) or the Drake as an input to an old ICOM R-7000!
> all-mode scanning receiver. The receiver is pretty deaf by many
> standards, and AO-40 was never more than an S1 or S2 on the meter,
> but it worked. (I've had AO-51 up to about S4 recently. Wow!)
>
>The transmit side starts in the shack with an ICOM 1271A tranceiver
>that I picked up from a fellow Ham last year. I'd never been on 1.2
>gHz before, so this was new territory. The tranceiver feeds a few
>feet of RG-8-like stuff (RG-214, I think) to get out of the shack,
>then there's about 60' of 1/2" hardline up to the roof, where it
>switches again to the RG-8-like stuff to go around the rotor and up
>to the antenna. The antenna is an 18 turn helix that I made from
>aluminum ground wire and wire ties. About 10 watts goes into the
>coax in the shack; not sure what makes it out the other end, but
>it's apparently quite sufficient for AO-51. I didn't have the 1.2
>gHz equipment when AO-40 was working, so I don't know how well it
>would have worked on the higher altitude satellites.
>
>The rotor assembly is home made; ham and tv-type rotors, run from a
>homebrew controller.
>
>Pictures at http://home.wavecable.com/~ko6th, at the bottom of the page.
>
>So, to answer your question, a lot of my getting on the microwave
>bands has been through stuff that I have built myself, with a few
>key components acquired opportunistically as they came around. From
>what I've seen recently, there are still downconverters to be had,
>as are the grill dishes, etc. Lots of folks have used the small 18"
>satellite TV dishes that many neighbors are giving away for
>free. The key is to be constantly hunting for stuff, designing and
>re-designing as you go, depending on what you can come up with.
>
>Hope this helps. Good luck!
>
>Greg KO6TH
>
>
>----------------------------------------
> > CC: amsat-bb@amsat.org
> > From: xunil@xunil.net
> > To: ko6th_greg@hotmail.com
> > Subject: Re: [amsat-bb] Re: Alone on L/S ON A0-51
> > Date: Sat, 13 Sep 2008 11:40:47 -0700
> >
> > Hi Greg-
> >
> > Too bad about the lonely pass. I haven't done a lot of research since
> > I (recently) got back into working the birds, but from what I remember
> > in the AO-40 days, my biggest problem working the microwave modes was
> > finding equipment. I remember Down East made microwave gear but they
> > were moving offices for what seemed like forever, and now it appears
> > they're swamped with backlog and aren't able to fill new orders.
> >
> > My question is, what L/S gear do you use, and where does one find
> > microwave gear these days?
> >
> > 73, Robert KC0KNM
> >
> > On Sep 12, 2008, at 8:45 PM, Greg D. wrote:
> >
> >>
> >> Hi Luc,
> >>
> >> Well, I guess the other parts of this planet are a bit more active
> >> than out here on the coast... Really nice 50+ degree pass this
> >> evening, and again I was all alone on LS.
> >>
> >> Greg KO6TH
> >>
> >>
> >> ----------------------------------------
> >>> From: lucleblanc6@videotron.ca
> >>> To: amsat-bb@amsat.org
> >>> Date: Fri, 12 Sep 2008 10:04:42 -0400
> >>> CC: eu-amsat@yahoogroups.com
> >>> Subject: [amsat-bb] Re: Alone on L/S ON A0-51
> >>>
> >>> On 11 Sep 2008 at 22:59, Greg D. wrote:
> >>>
> >>>>
> >>>> {snip}
> >>>>
> >>>>>
> >>>>> P.S. Remember, AO-51 is in mode J-FM on the 'QRP' side
> >>>>> (435.15/145.88)
> >>>>> this week.
> >>>>
> >>>> Also remember the main side is in LS. I had the whole bird to
> >>>> myself again tonight...
> >>>>
> >>>> Greg KO6TH
> >>>
> >>> Not quite VE3NPC,KD8CAO,WB8OTH,KC9ELU, and myself are there too
> >>> when they are able to find the right uplink on L... But if i can
> >>> succeed to
> >>> have the uplink controlled by a PC L/S will be a greath mode +-
> >>> path obstruction (Just hope they will put the sat in this mode
> >>> again this
> >>> winter)
> >>>
> >>> BTW I don't know the extent of L/S mode operation in europe and in
> >>> the rest of the world?
> >>>
> >>>
> >>> "-"
> >>>
> >>>
> >>> Luc Leblanc VE2DWE
> >>> Skype VE2DWE
> >>> www.qsl.net/ve2dwe
> >>> WAC BASIC CW PHONE SATELLITE
> >>>
> >>>
> >>>
> >>> _______________________________________________
> >>> Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the
> >>> author.
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> >>> program!
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> >>
> >> _________________________________________________________________
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